In the practice of biotechnology, nucleic acid fragments are commonly isolated from prokaryotic and eukaryotic and viral culures. The isolation of these fragments enables their sequencing, their use as probes for diagnostic and other research assays, and their assembly into genes encoding whole proteins or polypeptides. Traditionally, nucleic acids have been separated from contaminating proteinaceous material (e.g., from bacterial and viral cultures) by lysis in the presence of a detergent, (e.g. sodium dodecyl sulfate) and a salt solution, (e.g., potassium acetate) followed by extraction (deproteinization) with phenol or chloroform or a mixture thereof. These procedures separate the nucleic acids, generally by precipitation, from liquid and protein contaminants of the cell or virus culture.
A well-known and often-used example of this procedure applied to the isolation of plasmid DNA from bacterial cultures is described in H. C. Birnboim and J. Doly, "A Rapid Alkaline Extraction Procedure for Screening Recombinant Plasmid DNA." Nucleic Acids Res. 7:1513-1523 (1979). These two steps--lysis and deproteinization--have been separately performed because the reagents in the lysis steps are not miscible with the reagents involved in deproteinization. Consequently, the lysis and deproteinization of nucleic acids from contaminants requires a two-step procedure.